The present invention relates to drug-oligomer conjugates, and, more particularly, to growth hormone drug-oligomer conjugates.
Growth hormones have been used for replacement therapy in growth hormone-deficient children. Growth hormone is also under investigation as an adjunct in the treatment of several catabolic conditions such as burn injuries, surgery and malabsorption. The positive effects of growth hormone on calcium ion retention and on osteogenesis also may be of use in the treatment of osteoporosis and non-healing fractures.
Growth hormone may be administered by intramuscular or subcutaneous injection. Of these methods, subcutaneous injection may be preferred because it facilitates self-administration. However, both of these methods may be less than optimal because of the psychological and/or physical trauma that may be associated with administration by injection, especially in children.
Pharmaceutically active molecules such as proteins and polypeptides have been conjugated with polydispersed mixtures of polyethylene glycol or polydispersed mixtures of polyethylene glycol containing polymers to provide polydispersed mixtures of drug-oligomer conjugates. For example, U.S. Pat. No. 5,359,030 to Ekwuribe proposes conjugating polypeptides such as somatostatin, somatotropin and/or somatomedin with polydispersed polyethylene glycol modified glycolipid polymers and polydispersed polyethylene glycol modified fatty acid polymers. The number average molecular weight of polydispersed polymer resulting from each combination is preferred to be in the range of from about 500 to about 10,000 Daltons.
Polyethylene glycol (PEG) is typically produced by base-catalyzed ring-opening polymerization of ethylene oxide. The reaction is initiated by adding ethylene oxide to ethylene glycol, with potassium hydroxide as a catalyst. This process results in a polydispersed mixture of polyethylene glycol polymers having a number average molecular weight within a given range of molecular weights. For example, PEG products offered by Sigma-Aldrich of Milwaukee, Wis. are provided in polydispersed mixtures such as PEG 400 (Mn 380-420); PEG 1,000 (Mn 950-1,050); PEG 1,500 (Mn 1,400-1,600); and PEG 2,000 (Mn 1,900-2,200).
It is desirable to provide non-polydispersed mixtures of growth hormone-oligomer conjugates where the oligomer comprises polyalkylene glycol.
A mixture of growth hormone-oligomer conjugates comprising polyalkylene glycol according to embodiments of the present invention may exhibit higher in vivo activity than a polydispersed mixture of similar conjugates, where the polydispersed mixture has the same number average molecular weight as the mixture according to the present invention. This heightened activity may result in lower dosage requirements. Moreover, a mixture of growth hormone-oligomer conjugates comprising polyalkylene glycol according to embodiments of the present invention may be more effective at surviving an in vitro model of intestinal digestion than polydispersed mixtures of similar conjugates. Furthermore, mixtures of growth hormone-oligomer conjugates comprising polyalkylene glycol according to embodiments of the present invention may also result in less inter-subject variability than polydispersed mixtures of similar conjugates.
According to embodiments of the present invention, a substantially monodispersed mixture of conjugates where each conjugate includes a growth hormone drug coupled to an oligomer that comprises a polyalkylene glycol moiety is provided. The polyalkylene glycol moiety preferably has at least 2, 3, or 4 polyalkylene glycol subunits and, most preferably, has at least 7 polyalkylene glycol subunits. The polyalkylene glycol moiety is preferably polypropylene glycol. The oligomer preferably further comprises a lipophilic moiety. The growth hormone drug is preferably human growth hormone. The oligomer is preferably covalently coupled to an amino function of the human growth hormone. The conjugate is preferably amphiphilically balanced such that the conjugate is aqueously soluble and able to penetrate biological membranes. The oligomer may comprise a first polyalkylene glycol moiety covalently coupled to the drug by a non-hydrolyzable bond and a second polyalkylene glycol moiety covalently coupled to the first polyalkylene glycol moiety by a hydrolyzable bond. The mixture is preferably a monodispersed mixture and is most preferably a purely monodispersed mixture.
According to other embodiments of the present invention, a substantially monodispersed mixture of conjugates is provided where each conjugate comprises a growth hormone drug coupled to an oligomer including a polyalkylene glycol moiety, and the mixture has an in vivo activity that is greater than the in vivo activity of a polydispersed mixture of growth hormone drug-oligomer conjugates having the same number average molecular weight as the substantially monodispersed mixture.
According to still other embodiments of the present invention, a substantially monodispersed mixture of conjugates is provided where each conjugate comprises a growth hormone drug coupled to an oligomer including a polyalkylene glycol moiety, and the mixture has an in vitro activity that is greater than the in vitro activity of a polydispersed mixture of growth hormone drug-oligomer conjugates having the same number average molecular weight as the substantially monodispersed mixture.
According to other embodiments of the present invention, a substantially monodispersed mixture of conjugates is provided where each conjugate comprises a growth hormone drug coupled to an oligomer including a polyalkylene glycol moiety, and the mixture has an increased resistance to degradation by chymotrypsin when compared to the resistance to degradation by chymotrypsin of a polydispersed mixture of growth hormone drug-oligomer conjugates having the same number average molecular weight as the substantially monodispersed mixture.
According to yet other embodiments of the present invention, a substantially monodispersed mixture of conjugates is provided where each conjugate comprises a growth hormone drug coupled to an oligomer including a polyalkylene glycol moiety, and the mixture has an inter-subject variability that is less than the inter-subject variability of a polydispersed mixture of growth hormone drug-oligomer conjugates having the same number average molecular weight as the substantially monodispersed mixture.
According to other embodiments of the present invention, a mixture of conjugates is provided where each conjugate includes a growth hormone drug coupled to an oligomer that comprises a polyalkylene glycol moiety, and the mixture has a molecular weight distribution with a standard deviation of less than about 22 Daltons.
According to still other embodiments of the present invention, a mixture of conjugates is provided where each conjugate includes a growth hormone drug coupled to an oligomer that comprises a polyalkylene glycol moiety, and the mixture has a dispersity coefficient (DC) greater than 10,000 where   DC  =                    (                              ∑                          i              =              1                        n                    ⁢                                    N              i                        ⁢                          M              i                                      )            2                                ∑                      i            =            1                    n                ⁢                              N            i                    ⁢                      M            i            2                    ⁢                                    ∑                              i                =                1                            n                        ⁢                          N              i                                          -                        (                                    ∑                              i                =                1                            n                        ⁢                                          N                i                            ⁢                              M                i                                              )                2            
wherein:
n is the number of different molecules in the sample;
Ni is the number of ith molecules in the sample; and
Mi is the mass of the ith molecule.
According to other embodiments of the present invention, a mixture of conjugates is provided in which each conjugate includes a growth hormone drug coupled to an oligomer and has the same number of polyalkylene glycol subunits.
According to still other embodiments of the present invention, a mixture of conjugates is provided in which each conjugate has the same molecular weight and has the formula:
Growth Hormone Drug"Brketopenst" Bxe2x80x94Lhxe2x80x94Gixe2x80x94Rmxe2x80x94Gxe2x80x2jxe2x80x94Rxe2x80x2nxe2x80x94Gxe2x80x3kxe2x80x94T]pxe2x80x83xe2x80x83(A)
wherein:
B is a bonding moiety;
L is a linker moiety;
G, Gxe2x80x2 and Gxe2x80x3 are individually selected spacer moieties;
R is a lipophilic moiety and Rxe2x80x2 is a polyalkylene glycol moiety, or Rxe2x80x2 is the lipophilic moiety and R is the polyalkylene glycol moiety;
T is a terminating moiety;
h, i, j, k, m and n are individually 0 or 1, with the proviso that when R is the polyalkylene glycol moiety; m is 1, and when Rxe2x80x2 is the polyalkylene glycol moiety, n is 1; and
p is an integer from 1 to the number of nucleophilic residues on the growth hormone drug.
Methods of synthesizing mixtures of the various embodiments are also provided by the present invention.
Pharmaceutical compositions comprising conjugate mixtures of the present invention are also provided. Methods of treating a growth hormone deficiency in a subject in need of such treatment by administering an effective amount of such pharmaceutical compositions are also provided.
Methods of accelerating the growth rate of an animal by administering to the animal an effective amount of a mixture of conjugates according to the various embodiments described above are also provided.
Growth hormone drug-oligomer conjugate mixtures according to embodiments of the present invention may provide increased in vivo activity and/or lowered inter-subject variability and/or decreased degradation by chymotrypsin when compared to conventional polydispersed growth hormone drug-oligomer conjugate mixtures.